No abstract

Nitrogen sources with different properties and release characteristics are used to meet a variety of fertility management needs in turfgrass culture. Our objective was to determine the response of turfgrass to various urea‐formaldehyde reaction products; two particle sizes of oxamide; experimental sulfur‐coated ureas (SCU); products containing combinations of N sources; and an experimental composted sewage sludge. Nitrogen sources included for comparative purposes were isobutylidene diurea (IBDU); commercial SCU products; soluble sources; and Milorganite. In this 2.5‐yr study, 25 N source treatments were evaluated on ‘Merion’ Kentucky bluegrass (Poa pratensis L.) using 196 kg N ha−1 yr−1, split into two equal applications. Turf response was measured by weekly color ratings, weekly clipping yields, and N uptake for six growth periods during 2 yr. Urea‐formaldehyde reaction products containing no water‐in‐soluble N (WIN) gave results similar to those of conventional soluble N sources, while products containing WIN caused less initial color and growth responses, but gave a slight residual effect in the third year of use. Nitrogen uptake for powdered ureaform (66% of N as WIN) and the suspension FLUF (20% of N as WIN) was 44 and 75%, respectively, of that obtained with Formolene (0% WIN). Major differences in color and growth were found for the different particle sizes of oxamide, with the fine (<0.25 mm) material providing a faster release and less residual effect than the coarse (1‐3 mm) material. Turf fertilized with coarse oxamide responded similarly to that fertilized with coarse IBDU (0.7‐2.5 mm). Commercial SCU and fine particle SCU made with curtain granulated urea (94% of particles between 1.14 and 2.38 mm; dissolution rates: 6 and 15%) had pronounced residual effects, especially in the spring prior to fertilization. The experimental composted sewage sludge was inferior to Milorganite as a source of N for use on turf. N uptake with the compost treatment was only 32% of that obtained with Milorganite. Turf response from combinations of N sources generally reflected the amount and type of N source present. All N sources except the sludge compost were effective for turfgrass fertilization. Selection of an N source or combination of sources for turf fertilization should be dependent on quickness and duration of response desired, rate and frequency of applications, and various economic factors.

This study was conducted to determine the effect of various types and rates of soil reinforcing materials on soil bulk density, soil water content, surface hardness, and turfgrass density of a high‐sand root zone exposed to three levels of simulated traffic (wear). Six soil reinforcing materials were mixed at varying rates with a high‐sand root zone. These included DuPont Shredded Carpet, Netlon, Nike Lights, Nike Heavies, Turfgrids, and Sportgrass. Three levels of wear were imposed on each treatment. The types and rates of reinforcing materials had varying effects on surface hardness, bulk density, water content, and turf density of the root zone. Surface hardness and soil bulk density were correlated during the 2‐yr test period (r = 0.63). The reinforcing treatments that lowered soil bulk density and surface hardness were DuPont Shredded Carpet, Nike Lights, and Nike Heavies. Reinforcing material treatments that increased or did not affect soil bulk density generally resulted in increased surface hardness compared with nonamended controls. These treatments included Netlon and Turfgrids. Surface hardness generally became more pronounced as the level of wear increased for Netlon, Turfgrids, and Sportgrass treatments. The Sportgrass treatment consistently measured lower in soil water content than the control and had a turfgrass density lower than the control on all rating dates in 1996 but did not differ from the control in 1997. Athletic field managers considering using reinforcing materials should be aware that the type of material and rate influence athletic field surface hardness.

This study was conducted to determine: 1) if the Minolta CR-310 Chroma Meter can detect color differences among bentgrass (Agrostis stolonifera L., A. capillaris L.) cultivars maintained as a turf; 2) how the CR-310 parameters of hue angle, lightness, and chroma compare with visual color assessments; and 3) if the CR-310 can provide consistent color measurements among evaluators. Differences were detected among cultivars with respect to hue angle, lightness, and chroma. Hue angle and chroma were significantly correlated with visual color assessments when data were averaged across all evaluators. Lightness was not strongly associated with visual color assessment. Differences were found among evaluators for visual color assessment, lightness, and chroma, but not for hue angle measurements. Thus, hue angle appears to be the most consistent CR-310 parameter for measuring color of bentgrass turf. These results indicate that the CR-310 can be used to evaluate the color of bentgrass cultivars maintained as a turf and provides consistent hue angle measurements among evaluators, regardless of experience in rating turf color. The CR-310 is probably best used for measuring relative color differences and may be useful if cultivars of similar color are desired in blended turfs.

Irrigation water quality is one of the most important environmental issues facing the green industry today, especially in urban areas with competing interests for limited water resources. Fifty‐eight irrigation water survey kits were sent to golf courses within the Groundwater Protected Area of southeastern Pennsylvania. A total of 35 (60%) water samples were received and grouped into one of five water source categories: domestic, lake, recycled, stream, and well. Laboratory analysis measured or calculated 26 parameters for each irrigation sample and also rain water. For all samples, 22 of 26 parameters were observed within the normal range for turfgrass, but four parameters were not: pH, bicarbonate, iron, and nitrate. All irrigation water samples, however, were considered to be of acceptable to good quality for establishing and maintaining turfgrasses in southeastern Pennsylvania. Information from this survey was used to communicate proper irrigation water quality monitoring and environmental stewardship to the golf course segment of the green industry in southeastern Pennsylvania.